GER3688B - GE Generators - An Overview - GE Energy

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GER-3688B gle new design as compared to its predecessor. When these gains are compounded by the reduced number of unique designs, there is a pro found effect on the productivity and quality of the manufacturing operation. One of the potential adverse effects of stan- dardization can be a loss of flexibility to meet an individual customer’s needs. This has been addressed first by building into the design those features that are frequently specified. An example is the use of stainless steel oil feed piping. This fea- ture is not requested by every customer, but it is asked for often enough such that it is easier to build every unit with the stainless steel piping. The second way in which individual needs have been met is through “standard options.” These are pre- engineered options commonly requested for which drawings have been prepared ahead of time. These options can be readily incorporated in the machine, within normal material procure- ment and manufacturing cycles. An additional group of options is available that have not been pre-engineered due to the low frequency of request. These are available but with longer lead times since the necessary engineering work must be accommodated. DESIGN AND CONSTRUCTION FEATURES The design teams involved were organized with representation from all the major business functions, and members of the design teams visited some representative customers to better under- stand user needs. In this way, the technical requirements of the designs were influenced by the needs of all the functions involved in the design, manufacture, marketing and maintenance of the generator. Features were incorporated into the design specifically to aid producibility. Visits to and discussions with potential vendors influenced the design of components both for improved performance and to suit vendors’ capabilities. Careful cost comparisons were made of alternative design approaches to ensure that the final configuration was cost effective. ELECTROMAGNETIC DESIGN To achieve the reliability objectives of the pro ject, no new electromagnetic design limits have been used. The designs are based on proven technology used in generators already in service. Where appropriate, the technology used in larger units has been drawn upon to improve the designs of these machines. In reaching the final 4 configuration, a large range of design alternates was considered, and the final choice of design reflects the optimization of the types of considera- tion described herein. STATOR DESIGN The stator frame is divided onto an inner and an outer section, both of which mount on a single base fabrication. The inrrer frame is a very simple structure designed to support the stator core and winding while providing some guidance to the air flow in the machine. The stator core, made from grainoriented silicon steel for low loss and high permeability, is mounted rigidly in the inrrer frame. Isolation of the core vibration from the remainder of the structure is accomplished through the use of flexible pads between the feet on the inner frame and the base structure. The combined core and inner frame are designed to have a four-nodal natural frequency well removed from 100 Hz or 120 Hz, and tests on the assembled inner frame confirmed the predicted natural frequencies. The outer frame is a simple fabricated enclosure, which supports either the air inlets and silencers if the unit is open ventilated (Figure 5) or the roof and cooler enclosure if the unit is totally enclosed, water-to-air-cooled. The outer frame further acts as an air guide to complete the ventilation paths and as a soundproof enclosure to keep noise levels low. Since the rotor is pedestal mounted, the end shields are very simple struc- tures. As with the inner frame, the outer frame was designed to be free of resonances below 80 Hz, and again, tests of the completed structure confirmed the design analysis. The entire generator is mounted on a single fabricated base, which supports the pedestals, the inrrer and outer frames, and the brush rigging or the exciter. The base contains piping for oil sup plies, conduit for wiring and a number of compo nents associated with the main leads, such as light- ning arresters and surge capacitors. The structural vibration of the base was also confirmed by test to be well away from any frequency of concern. The stator winding is a conventional lapwound design. The insulating materials are those used since the early 1930s thus maintaining the proven reliability record. The materials are all designed and tested to provide reliable performance at Class F temperatures for the life of the machine. The stator bar copper is stranded and insulated with Class F materials and is Roebelled for mini- mum losses. The ground wall insulation is Micapal HT, a proven Class F system (Reference 1). This is a resin-rich tape system, with the volatiles removed under vacuum, which is then cured under pres-
JGEWERMRI ,YR -: sIL:zlc4 I 1 ; .:* I I I GENERATOR AIR lNLET n FILLER BETWEEN CROSSOVERS VERTICAL SEPARATOR GLASS TAPE -E ARMOR I TOP RIPPLE j SPRING FILLER/ J GENERAlOR CGMPIRTYEN, Figure 5. Generator packaging f STATOR SLOT ASSEMBLY / INSULATED TOUGH PITCH COPPER WIRE WITH ROEBEL TRANSPOSITION EPOXY IMPREGNATED MICA A TAPE GROUND WALL \RTD OR FILLER SIDE RIPPLE SPRING \ WEDGE Figure 6. Stator slot section GER-3688B GT18560 GT18494A-1
Page 1: GE Generators - An Overview James J
Page 4 and 5: GER-3688B restructure its aircooled
Page 8 and 9: GER-3688B STATOR PUNCHINGS--, VENTI
Page 10 and 11: GER-3688B COll Wedge creepage BlWk
Page 12 and 13: GER-3688B - G02A-00-043 / Figure 17
Page 14 and 15: GER-3688B Creepage Block Copper Wmd
Page 16: GER-3688B The design of modern gene

GER3688B - GE Generators - An Overview - GE Energy

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